http://hdl.handle.net/10451/3633 2013-05-23T20:51:45Z http://hdl.handle.net/10451/4583 Title: The effect of nitrogen source on photosynthesis of carob at high CO2 concentrations Authors: Cruz, C.; Lips, S. H.; Martins-Loução, M. A. Abstract: Carob seedlings (Ceratonia siliqua L. cv. Mulata), fed with nitrate or ammonium, were grown in growth chambers containing two levels of CO2 (360 or 800 μl l−1), three root temperatures (15, 20 or 25°C), and the same shoot temperature (20/24°C, night/day temperature). The response of the plants to CO2 enrichment was affected by environmental factors such as the type of inorganic nitrogen in the medium and root temperature. Increasing root temperature enhanced photosynthesis rate more in the presence of nitrate than in the presence of ammonium. Differences in photosynthetic products were also observed between nitrate- and ammonium-fed carob seedlings. Nitrate-grown plants showed an enhanced content of sucrose, while ammonium led to enhanced storage of starch. Increase in root temperature caused an increase in dry mass of the plants of similar proportions in both nitrogen sources. The enhancement of the rates of photosynthesis by CO2 enrichment was proportionally much larger than the resulting increases in dry mass production when nitrate was the nitrogen source. Ammonium was the preferred nitrogen source for carob at both ambient and high CO2 concentrations. The level of photosynthesis of a plant is limited not only by atmospheric CO2 concentration but also by the nutritional and environmental conditions of the root. Description: This paper is part of the contributions to the Proceedings of the 3rd International Symposium on Inorganic Nitrogen Assimilation, held in Tiberias, Israel, 6-11 September, 1992 1993-01-01T00:00:00Z http://hdl.handle.net/10451/4582 Title: The effect of NK fertilization on growth patterns and leaf nutrient concentration of carob-trees (Ceratonia siliqua L.) Authors: Correia, P. J.; Anastácio, L.; Martins-Loução, M. A. Abstract: The purpose of this experiment was to analyse soil nutrient availability as factors controlling vegetative and reproductive growth in carob {Ceratonia siliqua) trees. The orchard with 10 year-old trees, was established on a calcareous soil (total calcium carbonate: 65.2 %; active lime: 17.5 %). Four fertilization levels were tested: no fertilizer (C); 0.8 kg N.tree-1 (N treatment); 1 kg K20.tree-1 (K treatment) and 0.8 kg N.tree-1 plus 1 kg K20.tree-1 (NK treatment). No irrigation was applied during the experimental period. Branch length increment, inflorescence number, leaf area index, fruit and leaf mineral content were registered. Correlations between growth patterns and climatic variables were evaluated in order to discriminate between fertilization effects and abiotic stress, typical of Mediterranean climate, such as drought. The preliminary results of a NK fertilization trial are here presented and tree responses to N and K application were discussed in terms of source-sink effects, namely vegetative versus reproductive growth. The knowledge of these growth patterns could be important for making decisions related to fertilization. Thus, modifying orchard fertilization regimes may be a helpful strategy to improve yield on these particular droughty sites. Description: ACESSO via B-on: http://dx.doi.org/doi:10.1007/978-0-585-37449-9_7 1999-01-01T00:00:00Z http://hdl.handle.net/10451/4581 Title: La fijacion biologica de nitrogeno atmosferico y la produccion vegetal Authors: Rodríguez-Barrueco, C.; Subramaniam, P.; Martins-Loução, M. A. Abstract: Biological Nitrogen Fixation shows itself as a promising means to lower costs in plant protein production. It offers the scientist with a wide spectrum of possibilities to develop, by further research, what is already known on that process. Meanwhile, nitrogen fixation must be put to work and to that end a range of biological systems existing in Nature are outlined, though briefly, in the present article, mainly covering symbiotic, as well as free-living nitrogen-fixers. The use of synthetic nitrogen fertilizer is at stake due to increased fossil fuel prices, and trying to bring up new, not so costly alternatives, appears to be the point at issue. Suggestions on the use of the various systems, supported by experimental data, are given, and the attention of the reader called upon those points which should merit further research. La Fijación Biológica de Nitrógeno se muestra como un medio de reducir costes en la producción de proteína vegetal. El científico dispone de un amplio campo donde desarrolar unas investigaciones que se encuentran en constante dinâmica. Mientras tanto, la fijación de nitrógeno ha de utilizarse en la práctica al nivel que los conocimientos actuales nos lo permitan. Con este propósito se incluyen una serie de sistemas naturales capaces de ejercer aquella función, principalmente simbióticos y libres, respectivamente. El uso de fertilizantes nitrogenados de síntesis industrial se presenta cada día más problemático debido a los precios de los combustibles fósiles. Por ello han de desarrollarse nuevas alternativas, no tan costosas, sustitutivas, o en su caso complementarias. Se mencionan las posibilidades que los distintos sistemas nos ofrecen, apoyadas en resultados experimentales, así como aquellos aspectos del processo que merecen la atención del investigador. 1982-01-01T00:00:00Z http://hdl.handle.net/10451/4580 Title: V.2 Carob (Ceratonia siliqua L.) Authors: Martins-Loução, M. A 1989-01-01T00:00:00Z